Electronic commutator



July 4, 1950 A. H. DICKINSON ELECTRONIC COMMUTATOR Original Filed Dec. 27, 1943 w E? V T? V $2 V Ni w NE Tw INVENTOR (1. W M

ATTORNEY Patented July 4, 1950 ELECTRONIC COMMUTATOR Arthur H. Dickinson, Greenwich, Conn., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Original application December 27, 1943, Serial No. 515,719. Divided and this application November 25, 1949, Serial No. 123,436

13 Claims.

This application is a division of my application Serial No. 515,719, filed December 27, 1943, for Electronic Accounting Apparatus.

The present invention involves a novel electronic commutator used in said electronic accounting apparatus and having general utility as a distributor of potential. This electronic commutator presents improvements over the electronic commutators of my prior application Serial No. 394,884, filed May 23,1941, as well as over other electronic commutators in the prior art.

The electronic commutator comprises a plurality of interconnected electronic triggers. Each trigger is composed of a circuit which in cludes a trigger pair of electron units or tubes which are cross-tied, anode of each to a control electrode of the other, to produce either one relation of opposite conductive conditions of the trigger pair of tubes or a reverse such relation,

whereby the trigger has two, alternative states determined by the two different relations in conductivity of the trigger pair of tubes. Tripping of the trigger from one of itsstates to the other is effected by changing the relative conductivity of the trigger pair of tubes.

The present invention is featured by a novel method and means for effecting the change in relative conductivity of the trigger pair of tubes.

According to the invention, the triggers in the commutator are coupled in a novel series chain fashion.

More specifically, the invention provides a novel pattern of connections, from trigger to trigger, which consists of separate connections from the anodes of both tubes of a trigger pair to control electrodes of the two tubes in another trigger pair. By means of this pattern of connections, each trigger pair of tubes depending on its relative condition of conductivity primes or influences a next trigger pair of tubes for either a change in one direction or in an opposite direction of the relative condition of conductivity of the influenced trigger pair.

One state of the trigger may be named, for convenience, an off state and the alternative state may then be called the on state. Using these terms, the invention provides such a pattern of priming connections from anodes of one trigger pair of tubes to control electrodes of a next trigger pair of tubes that when one trigger is in one state it primes the trigger pair of tubes of the next trigger, if this trigger is ofi, towards reversal of this next trigger to on state; but if the priming trigger is in its alternative state. then it primes the trigger pair of tubes in the next trigger, if this trigger is on, towards reversal of this next trigger to oil state. This next trigger similarly primes the trigger pair of tubes in a following trigger, and so on.

According to the invention, a closed ring of such priming pattern of connections is provided by which a chosen last trigger of the commutator when in off state primes the cross-tied, trigger pair of tubes of the first trigger for reversal from oil to on state, the first trigger thereupon similarly primes the second trigger for reversal from 011 to on state and so on till the last trigger is reversed to on state, the last trigger thereupon priming the trigger pair of tubes in the first trigger for reversal from on to off state, the first trigger then similarly priming the second tube for reversal to 011 state, and so on. In this manner, the triggers are sequentially primed and turned to on state and then sequentially primed and turned back to off state, in repetitive fashion. According to the invention, driving pulses for efiecting the actual reversals of the triggers when primed are simultaneously applied to control electrodes of-all the tubes tied into trigger pairs. Each such driving pulse is effective in conjunction with the priming potential applied to one trigger pair of tubes at a time, in the sequential priming pattern, for changing the relative condition of conductivity of the primed pair of tubes and thereby effecting the reversal in state of the trigger containing this primed pair of tubes.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated of applying that principle.

In the drawings:

Fig. 1 shows the commutator circuit.

Fig. 2 is a chart of voltage conditions at anode points of the trigger pairs of tubes during a commutator cycle.

The illustrated device has five stages each com-- prising an electronic trigger circuit which may simply be called a trigger. The first stage or trigger is designated AG-l, the second A'|--2, the third A8--3, the fourth A94, and the fifth A05. The triggers are across line 50 and line 5| which are supplied with suitable D. C. voltage. Across lines 50 and 5| is a voltage divider comprised of resistors 55 and 51-58, the junction of these resistors being tapped by the cathode voltage line 6|.

The anode of each tube isconnected to line 59 by the resistor 62 of the same branch.

The grid of the tube in one branch is connected to the point 67 of the opposite branch. The two tubes 68L and 58R which are thetrigger pair,

are shown as a twin triode,,and: their common cathode connects to line It is understood that, if desired, the tubes may be in separate .en-

4 through resistor 52L and the tube to line 6 I. The potential at point EEL'drops rapidly, feeding a negative pulse through condenser 65L, to point 62L. Thereupon, the potential at the point fills and, hence, the grid potential of tube 55R decreases suddenly to cut-off" value and current flow in 58R ceases substantially instantaneously.

Point 65R has an accompanying rapid rise in potential, and the resulting positive pulse is fed by condenser 55R to point 611R, promoting the increase in grid potential of tube 58L which wasinitiatedbythe application of positive potential to point Tube $381: is now conducting and tube 583 is off, the reverse of the previous status of the tubes. In this manner, adequate gpositive potential" applied to point 57R, has tripped the trigger from off state to on state. To

velopes, each tube with. its own cathode to' be connected to line 5!. Each tube is so chosen as to be conductive when its grid is substantially cathode voltage; that "is when the grid bias is substantially zero. are so chosen that Whenone of the tubes is at cutoff, the grid bias of the opposite tube will be substantially zero'andthe latter tube will be conductive; i.-e.,-at low impedance. Anefficient value relationship is one in-vfhich resistors 69. and 64 are equal in value, resistors as are approximately three times this value, and condensers 65 have a'capacity of the order of a few hundred micromicrofarads. A tube may 'bere ferred to as on whenit is conducting-current, and as oii when it is at cut-off. Each branch may bereferred to as on or off according to whether its tube is on or-ofi. For convenience, the trigger circuit unit will be considered as on or OK in accordance with the on or off status of the left hand branch.

In further explanation, assume tube S83; is on. Accordingly, its impedance is low and the potential at anode-connected pointfiiih" is then only slightly above cathode potential- "The accom-- panying potential drop across resistors 83L and on, forces the potential at point 67L below that of cathode line 6!. Since 'the'grid of tube EiiRis connectedto point 53L, the grid will'at this time be biased sufficiently negative to maintain tube 68R ofi. The tube 683, being off, its impedance is high and the potential "at anode-connected point 66R is also high. The accoinpanying p0 tential drop across resistors 83R and E 'iL does not force the potential at point below cathode potential. Since the grid of tube teL is-connected to point (NB, the potential then-existing at this point is sufficient to hold the grid at'zero bias, so that tube 58L will be maintained conductive. In this manner, tube ESL when on maintains thefifiR oii and, conversely, tube 83 in off status maintains 131113663L 'in'on status. The tubes in this relative status establish one state of stability of the trigger circuit unit; namely, the on state. Inthe reverse state of stability; that is, in theofi state'oi the circuit, tube 68R will be on'and tube 69L will be oh. Also, the voltage values at the corresponding points of the two branches will be reversed and the interconnections between the branches will maintain the circuit in ofi state.

The trigger may be reversed from off state, in which tube 63L is at cut-off and tube "68B, is conductive, by impressing positive potential on point 61R. of sufiicient amplitude to raise the grid poe tential of tube 68L above cut-off value. Tube 68L starts to conduct current from line '52 Thevalues oi the elements iii) trip the trigger back from on to off state adequate positive potential may be applied to point ML. The grid of tube 683 thereupon is increased in potential to start current flow through this tube. Ina manner'now clear, the shift in status will continue until tube-68R is again conductive and tube 68L is again off; i.-e., the trigger has been switched back, by positive potential applied to point en. from on to on state.

A glow lamp "i8 is connected, inseries with a current limiting resistorpbetween line Bil and point 68L. When the trigger is oil, point {36L is at high potentialfand the difference of potential across the lamp is insufficient to ignite .thelamp. When the trigger is on, point 66L is at low potential and there is enough difference in potential across the lamp to ignite it, thereby visually indicating the on status of the trigger.

Instead of reversing the trigger by applying positive potential to the grid of its non-conducting tube, the same effect can be obtained by applying negative potential to the grid of the conducting tube. When-positive potential of sufficient amplitude is applied to thegrid of the nonconducting tube, a regenerative. action in the rigger is initiated for cutting off the conducting tube. When negative potential of suflicient amplitude is applied to the conducting tube of a trigger, a regenerative-actionisinitiated for raising the grid potential of thenon-conducting tube above cut-off. In the present embodiment, posiive potential of adequate. amplitude will be applied sequentially tothe successive triggers in the commutator for eiiecting sequential reversals of the triggers. For eil'ecting a concurrent reversal of the triggers to on or reset status, a negative pulse of adequate potential will be appliedsimultaneously to the grids of all the tubes 68L of the triggers. I

According to the invention, the application of positive tripping potential to a grid of a tube in each trigger will take place in two steps. The first step is to produce a preparatoryor priming-risein grid potential of the non-conducting tube of a trigger pair; [This priming rise will be produced by a preceding trigger in the ring of triggers forming the commutator. The priming rise of itself will be inadequate to increase the grid potential abovecut-ofi and the trigger will be unreversed. The second step is to apply a positive pulse to the grid. Of itself, the positive pulse will have insuiiicient amplitude to raise the gridpctential of anon-conducting tube above cutoff. Only'whenthe pulse is. applied on top of the priming rise will the grid be driven'above cutwli. In other words, the priming rise onfthe grid of a non-conducting tube combined. with .or supplemented by the additive effect of the positive potential to drive the grid above cut-off", causing the tube to conduct and the trigger to reverse.

The positive pulses are applied to a common input line 9610 of the commutator. As will be brought out, each pulse is fed simultaneously to the grids of all the tubes of the trigger pairs. The pattern of priming connections is such that priming potential will be applied to the grid of only one non-conducting tube at a time of all the triggers in the commutator. Hence, each pulse although fed simultaneously to the grids of all the tubes will be effective to raise only the primed grid above cut-off potential, causing its tube to conduct and the trigger containing this tube to reverse. By this means, the triggers may be sequentially primed and reversed even though input pulses are each simultaneously applied to the grids of all the tubes in all the triggers.

The commutator circuit will now be described in detail.

The pattern of priming connections includes a resistive connection Ma between point ML of the first trigger At-l and point 61L of the second trigger Al-2. Since point 66L is connected to the anode of tube ESL and point 67L is connected to the grid of tube 5&3, the resistive connection we is between the anode of tube ML of the first trigger and the grid of tube 58B of the second trigger. A similar connection is provided from the anode of ESL of the second trigger to the grid of 68B of the third trigger A8-3, between the anode of ESL of the third trigger and the grid of 68B of the fourth trigger A9 l, and between the anode of 58L of the fourth trigger and the grid of 681% of the fifth or last trigger A!l-5. The point 65L and, hence, the anode of tube 68L, of the last trigger is connected by a resistor MI) and wire 35 to the point 67R and, hence, the control grid of tube 68L, of the first trigger A6l. In s'hort, the successive triggers are connected, anode of each left hand tube 63L to grid of each right hand tube 68R, but the anode of the left hand tube ESL of the last trigger in the series is connected to the grid of the left hand tube ESL in the first trigger.

The point 66R and, hence, the anode of 68B, of the first trigger is connected by a resistor Mb to the point NR and, hence the grid of ML, of the second trigger. A similar connection is provided between points 68R and 67B of the second and third triggers, third and fourth triggers, and fourth and last triggers. The point 66B of the last trigger, however, is connected by a resistor 14a and line 39 to the point 61L of the first trigger. Thus, the anode of the right hand tube of each trigger except the last is connected to the grid of left hand tube of the next trigger, but the anode of the right hand tube of the last trigger is connected to the grid of the right hand tube of the first trigger.

The point 66L or MR of a trigger is at high potential depending on whether the trigger is oil or on, respectively. By reason of the described pattern of connections between triggers, the high potential at a point 65L or 66R of each trigger will be transmitted to a grid of a tube in the next trigger in the ring of triggers and will provide the priming potential for this grid. If the grid is in a non-conducting tube, then the applied priming potential added to the efiect of an input pulse received by the grid from wire Btu will render the tube conductive, but if the grid is in an already conducting tube, it will experiasi ro'st enc'e no change from the combined effect of they priming and pulse potentials applied to the grid.

The input pulses on line 961; are each simultaneously applied to points ML and 67R via parallel condenser-resistor connections Ha-Ha- Assume all the triggers are off, so that all the points 61L are at high potentiaL Accordingly,

each of the triggers, except the last trigger All-5,. is applying priming potential to the grid of the already conducting tube in the next trigger, but the last trigger A@5 is priming the grid of the non-conducting tube ESL in the first trigger A6-i. Hence, the first following pulse, although;

simultaneously applied to all the grids, takes ef-- fect only on the primed grid of tube ESL in thefirst trigger A6l, causing this primed grid to rise above cut-off potential, whereupon tube 68L;

becomes conductive and trigger Ail-l reverses from off to on state (see Fig. 2). The first pulse has thus turned on only AE-I. When Ail-l is in on state, its point 66R is at increased potential and its point Gill; at reduced potentiaL. Hence, priming potential is removed from point E'lL of Al2 and is applied now to point 63B of Ai2. The second pulse on wire $510 therefore will turn on A'l2. The pulse will have no effect on the other units. For instance, unit A6! is still primed at point 61R so that the pulse can be effective only to turn on this unit,

a status which it already has. Units A6----! and Al-2 are now on and the remaining units oil. It will be clear now that a third pulse will turn on A33, a fourth pulse will turn on A9 i, and a fifth pulse will turn on Ail5. With fit-5 on, its point 56R is at increased potential and applying priming potential to point 61L of Afi-l. Hence, the sixth pulse will turn oil At-I. With A5l off, it is priming point ML of All-2. Accordingly, the seventh pulse will turn off Al2.

Similarly, the eighth and ninth pulses will turn on" A3--3 and A9-4 successively. The tenth pulse will turn off Ail-5. This completes a comniutator cycle, all. the triggers having returned to their initial off state.

While each pulse is impressed on the grids of allthe triggers simultaneously, each pulse can reverse only a single trigger. Thus with A6-! primed at its point 61R, the first pulse initiates the tripping of this trigger toon status. Point 66R of All-4 rises in potential exponentially, with an attendant exponential rise in potential of point 61R of Al-2. As the potential on point MB of Al2 is rising, the first pulse is receding. By the time point 61R of A'!2 has attained effective priming potential, the first pulse has declined in power and has ceased to exist, for practical purposes. Thus, this pulse will be un able to turn on Al'--2. Similarly, each of the successive pulses will turn on only one trigger and will become powerless before the trigger be ing turned effectively primes the next triggen.

the triggers initially are all in off status or in ar ses-7- yl he to e. des ribed r at v s e W h n. e qmnutatcr; sequ nce: hs s rdt nche Qith t i e s thew- 11.1 rn du cessively to the same status, each as it-turns to s e, rin in about anaccompanying change in its companion branch to theopposite state. Thus, if the triggers'are all ofi initially,

the pulses thereafter applied turn on the left.

handbranches of the triggers successively and then -turn on the right hand branches-succes sively; Of the ten branches, a groupof onlyfive.v is in thesame state at any onetime. Successive,

position to a next position upon successive steps of operation of the network of branches.

In a manner described in detail inmy parent application Ser. No. 515,719, when it is desired to reset the commutator; i. e., to return all the triggers to .off states, a negative pulse of adequate amplitude is applied to a wire 20m. Condensers 262 and resistors 203 couple wire 201a to the points 81B of triggers A6l to A07-5. By this circuit arrangement, the negative pulse appearing on wire 201a is simultaneously applied to the right sides of all the triggers. any of said. triggers which are on are now tripped off concurrently.

While there have been shown and described ThllS,

and'pointed .out the fundamental novel features 7 necting the devices,,anode to control electrode,-

to form trigger pairs; and. means connecting the devices of different trigger pairs together in an endless chain operative series,.said .chain connections beingfrom the, anodes of both devices. ina pair to thecontrol .electrodesof both devices ,in another pair.

2. In combination, a plurality. of vacuumtubes, each having at least ananode, a cathode and a controlgrid; means-connectingthe tubes in trigger. pairs, .with the anode of .eachtube of a pair connectedto thecontrol gridof the.

othertubeof the pair; and means connecting the difierentpairs together in an endless chain op-- erativese ucnce in which the anodesof the tubes.

of a trigger pair are connected to the control grids of th e tubes of another trigger pair and can control the effect of the control grids to select the pairs for sequential operation,

3. In combination, a pluralityof pairs of electronic devices, each device having an anode, 1

a cathode, and means to control conductionbea tween the anodeand the cathode; meanscondevices of a pair and the control-means-of a difierentlpair, ,the priming and trigger bounce-- tions-cooperating-to provide a blocking bias for the control means ,of the devices of all pairs except the one pair nextto be operated and pro-. viding the control means of this one pair with a controlwhich allows it to be operated quickly in respenseto an input impulse, and the pattern of the. priming connections being such that the pairsrare. rendered ,operable oneafter another to respond vto inputimpulses; and means common to all the devices to impress input pulses on the control means of all the devices to cause theprimed pairs to operate.

4.111 combination, a plurality of electronic devices, each device including an anode, a cathode, and means to control conduction between the anode and the cathode; means connecting the devices in pairs, anode to control means, to formtrigger pairs in which one of the devices is conducting and theother device is non-conducting andin which the conducting and nonconducting condition of the devices of a pair can be reversed when the pair responds to an input impulse; means for applying input impulses to the controlmeans of all the devices of the pairs, which impulsesare ineffective to cause a reversal of theconducting condition of the pairs; and meansto connect the anodes of a pair to the control means ,of another pair to control the effectiveness of the control means and thereby selectively prime the trigger pairs one after another to enable the input impulses to be effective thereon. to cause them to operate and reverse the conducting andnon-conducting condition of their, constituent devices.

5. In combination, a plurality of electronic devices, eachdevice having an anode, a control grid, and means to control conduction between the anode and the cathode; means for supplying operating potentials for the anodes, cathodes, and control means of the devices; means connecting .the devices to form an operative ring and to control their conduction, including anode-tocontrol-means trigger connections for connecting devicesv to form trigger pairs, in each of which, pairs one of the devices is conducting and the other device is non-conducting, which condition of the devices can be reversed upon an operation of the pair, and resistance. network connections between the anodes of the devices of a pair and the control means of the devices of another pair for connecting the devices in a serial pattern, the trigger connections and resistance network connections controlling the controlling means of the devices to render the pairs of devices responsive to input impulses one after another in sequence and to provide an overbias on the remaining pairs at each stageof operation of the ring to prevent them from responding to input impulses impressed on the control means and render" the devices stable against "misoperation; and means to impress input impulses on the control means of the devices, each of which impulses is impressed on the control means of all the devices and causes the pair whichis responsive to operate.

6. In combination, a plurality of electronic devices, eachdevice containing at least an anode, a cathode; and control means; means normally supplying anode-cathode. potential and biasing potential for thecontrol means of said devices; means connectingth-e devices for controlling conducting therein, including connections connect-.

ingthedevices ,anodeto control means, in trigger pairs, and,also.includingpriming network con-,

nections between theanodes of the devices ofv I the pairs and the control means of thedevices of other pairs for modifying th control of the con trol means to enable the trigger-pairs to be responsive and change their mode .of operation one after another in succession in response to impulses impressed on the control means of all the devices; and means to impress impulses on the control means of the devices to cause their operation, each impulse being impressed on the control means of all the devices and causing the trigger pair, which is primed at that time, to operate. 7

7. In combination, plurality of electronic devices, each device including at least an anode, a cathode, and a control means; means connectingthe devices to form trigger pairs by conductively coupling the anode of each device of the pair to the control means of the other device of the pair so that, at any instant, but one device of a pair will be conducting and so that, when primed, a pair can respond to an input impulse and can change its mode of operation; means also conductively coupling the control means of a device on one pair to anode of a device of another pair to form an endless operating chain of the devices and to enable the pairs of devices to be primed, the pattern of the priming connections being displaced from the pattern of trigger connections insuch a manner that, at any stage of operation of the pairs of devices, the conduct-' ing device of only one pair will have its control means connected to the anode of a conducting device of another pair and the non-conducting device of said one pair will be the only non-conducting device having its control means connected to the anode of non-conducting device of another pair, which condition causes said one pair to be primed to respond to an input impulse and to change its mode of operation, said one pair when operated being effective to cause a further pair to be primed; and means common to all the devices to impress input impulses on the control means thereof to cause the sequential change in the mode of operation of the pairs,

8. In combination, a plurality of vacuum tubes including at least an anode, a cathode, and a control grid; means for supplying operating potentials for the tubes and including an individual resistance for the anode of each tube whereby the potential of the anode of a tube will vary with its conductivity; means connecting the tubes anode to control grid to form trigger pairs in which, at any stage of operation of pair, one or the other of the tubes is conducting and the other is non-conducting; and priming connections between the trigger pairs to connect the tubes in an operative ring and render the pairs selectively operable to change their mode of operation one after another, said priming connections extending from the anodes of the tubes of one pair to the control grids of the tubes of another pair and being of such a pattern that, at any stage of operation of the ring, only the primed trigger pair will have the control grid of its conducting tube connected to the anode of a conducting tube of another pair to make the potential of the control grid of the conducting tube of the primed pair less positive than the control grids of the other conducting tubes, and only the primed trigger pair will have the control grid of its non-conducting tube connected to the anode of a non-conducting tube of another pair to make the potential of the control grid of the non-conducting tube of the primed pair less negative than the control grids of the other non-conducting tubes, whereby the primed pair can "respond to an input impulse and can i change its mode of operation.

9. In combination, a plurality of electronic devices, each device including an anode, a cathode, and a control means; means connecting the devices to form trigger pairs in which, at any stage of operation of a pair, one or the other of the devices is conducting and the remaining device is non-conducting; priming network connections including conductive couplings between the anodes of the devices of a pair and the control means ofthe devices of another pair for connecting the pairs in a ring and for rendering the pairs selectively operable one after another in response to input impulses, said priming network connections being of such av pattern that they are effective at any stage of operation of the ring to cause the control means of the devices of all the pairs except the primed pair to have potentials applied thereto which prevent these pairs from responding to input impulses and changing their mode of operation; and means coupled to the control means of all the devices to apply inputimpulses to all the devices, each impulse being impressed on the control means of all the devices and causing the devices of the primed pair to operate and change their mode of operation. v

10. In combination, a plurality of electronic devices, each device having at least an anode, a cathode, and a control electrode; means connecting the devices to formtrigger pairs in which one device of a pair is conducting and the other device of the same pair is non-conducting and in which the conducting and non-conducting conditions of the devices of a pair will be reversedeach time it operates in response to an input impulse; priming network connections including connections between the anodes of the devices of a pair and the control electrodes of the devices of another pair for connecting the pairs in a ring and for selectively rendering the pairs responsive one after another to input impulses, said network connections causing the control electrodes of all the pairs except the primed pair to be over-biased and stable against operation to allow only the primed pair to respond quickly to an input impulse and the pattern of the network connections causing the primed pair, when operated, to be given an overbias and one of the previously over-biased pairs to be primed and made responsive to an input impulse whereby the ring is controlled for stepby-step operation of the pairs; and means to impress input impulses on the control electrodes of all the devices.

11. In combination, a plurality of electronic devices, each device having at least an anode, a cathode, and a control electrode; means to provide operating potentials for the devices; means to connect the devices, anode to control electrode, to form trigger pairs in which, at any stage of operation of a pair, one device of the pair is conducting and the other device is non- COIldllCtiIl g and in which the conducting and non-conducting condition of the devices of a pair will be reversed each time it operates in response to an input impulse; priming network connections between, the anodes of the devices of a pair and the control electrodes of the devices of another pair for connecting the pairs to form a ring and to render the pairs responsive one after another in endless sequence in response to input impulses, said priming connections causing at 11 least one, control electrode in/all pairs'exceptthe primed pair to have a potentialwhichwillprevent these pairs fromoperatinginresponse to' ,input impulses and causing the controlelectrodes of the primed pair: to have-potentials which .will allowpthe primedpairto respond quickly to an input impulse," and said priming network conections' having a-;pattern by which the pairs are primed for operationone after another; and means common-to all the devices for supplying the 'control electrodes of the devices with input impulses which can cause an operation of the primed pair but which are not sufficient to overcome-the blockingpotential in the ing network connections, including connections between theanodes of=the tubes of a-pai-r and the control grids of the tubes of another pair, for

connecting the pairs in a ring and for selectively rendering the pairs responsive one after another to input impulses, sa'id -'-n'etwork connections causing the control grids of all the pairs except primed pair to -be over-biased andstable against operation to allowonly the primed-pair to respond quickly to an input impulse, and the-pat- -tern of the network connections causing the primed pair, when operated, to be given-an overbias and one of the'prev-iously over-biased pairs 1 to be primed and'made responsive'to an input impulse whereby the ring is-co'ntrolled' for "stepby-step operation of the pairs; and means to impress input impulses on'the control grids of allthe tubes.

13. In a batteryoperated vacuum tube ring,

' the combination of a plurality of battery operated vacuum tubes; each tube having an anode, a cathode, and means to control conduction between'the anode and the cathode; means for supplying operating potentials for the anodes, cathodes, andcontrol means of the tubes;=means connecting the tubes to form an operative ring and to control their conduction, including anodeto-control-means trigger connections for connecting tubes to form trigger pairs, in each of which pairs one of the tubes is conducting and the other tube is non-conducting, which condition of the tubes can be reversed upon an operation of the pair; and resistance network connections between "the anodes of the tubes of a trigger pair and the control means of the tubes of another trigger pair for connecting the tubes in a serial pattern in a, ring, the trigger connections and resistance network connections controlling the controlling means of the tubes to render the pairs of tubes responsive to input impulses one aiter another in sequence and to provide an over-ebias on the remaining pairs of tubes at each stage of operation of the rin to prevent them from responding to input impulses impressed on the control means and render the trigger pairs stable against misoperation; and

means to impress input impulses on the control means of the tubes, each of which impulses is impressed on the control means of all the tubes and causes the pair which is responsive to operate.

ARTHUR H. DICKINSON.

No references cited. 

